I agree that using some form of device such as SAM puttlab can be helpful, however putting is so feel based that some people can get wrapped up to much in the numbers and not in how the putter feels, looks, sounds etc. Keep in mind that a putter is the only club you use on every hole and having one that you like the look of, can aim well and start the ball on line is what’s going to help lower scores.
For when doing a putter fitting I look for two things: 1) the ability to try different grips and 2) try the putter on an actual putting green. To that, since you live in Melbourne, I’m assuming Florida and not Australia, you should check out Tour Spec Golf at Lake Nona in Orlando. They have an awesome setup and can easily change head, shaft length and grip versus just trying what’s on the rack.